Deterioration of critical infrastructure—such as bridges, pipelines, and railways—is a common, yet complex problem. Currently, manual inspection is the most common practice used to monitor the structural integrity of structures such as bridges. However, manual inspections have proven to be insufficient to ensure the safety of structures. Such inspections do not provide enough information to prevent catastrophic failures.
To ensure public safety and the continuous serviceability of critical structures such as bridges, it is imperative to develop cost effective and reliable technologies that regularly assess their structural health and integrity.
Beyond manual inspections, other existing techniques for structural health monitoring suffer from non-scalability due to the high cost of instrumentation devices, large installation costs (e.g., due to wiring needs), or high maintenance costs. Although some solutions have offered sensors with wireless communication technologies, such solutions require batteries in the sensing devices, which limit the functionality of such solutions, and requires battery replacement.
Some example conventional systems and methods for monitoring a structure will now be described with reference to FIGS. 1 and 2.
A first conventional system and method for monitoring a structure will now be described with reference to FIG. 1.
FIG. 1 illustrates an example conventional monitoring system 124 for monitoring the structural health of a structure 100.
As illustrated in the figure, structure 100 is monitored by conventional monitoring system 124, which includes sensors 102, 104, 106, 108 and 110, a data processing unit 112, and wires 114, 116, 118, 120 and 122.
Sensors 102, 104, 106, 108 and 110 are arranged to be in contact with structure 100 at positions of interest. Data processing unit 112 is arranged to be installed in proximity of structure 100.
Sensors 102, 104, 106, 108 and 110 are operable to detect parameters of structure 100 related to its structural integrity. Each of sensors 102, 104, 106, 108 and 110 may detect one or more parameters, but not necessarily the same parameters, related to structural integrity of structure 100. Data processing unit 112 is operable to read the parameters detected by sensors 102, 104, 106, 108 and 110.
Sensor 104 communicates with data processing unit 112 through wire 114. Sensor 116 is connected to data processing unit 112 through wire 116. Similarly, sensors 100, 102, 108 and 110 use wires to communicate with data processing unit 112.
In operation, conventional structural health monitoring system 124 monitors structural health and integrity of structure 100 by gathering and processing information from sensors 102, 104, 106, 108 and 110. For example, if sensor 102 is capable to monitor strain, it regularly provides readout of strain to data processing unit 112. Then data processing unit 112 may develop baseline range for normal strain readout for sensor 102 by examining long term readouts of sensor 102. After developing the baseline range, if the strain readout of sensor 102 is outside the normal baseline range, data processing unit 112 may generate an alarm. In a similar manner, data processing unit 112 processes data provided by sensors 104, 106, 108 and 110.
Structural health monitoring of a large structure similar to a bridge requires a large number of sensors similar to 102, 104, 106, 108 and 110 installed at distributed points of the structure; therefore, the cost of the conventional structural health monitoring system 124 becomes significant due to the cost of installing and maintaining the wires on the structure.
In another conventional structural health monitoring system, the information is passed wirelessly between the processor and the sensors. This will now be described with reference to FIG. 2.
FIG. 2 illustrates another example conventional monitoring system 212 for monitoring the structural health of structure 100.
As illustrated in the figure, structure 100 is monitored by conventional monitoring system 212, which includes wireless sensors 200, 202, 204, 206 and 208 and data processing unit 210.
Sensors 200, 202, 204, 206 and 208 are arranged to be in contact with structure 100 at positions of interest. Data processing unit 210 is arranged to be installed in close proximity of structure 100.
Sensors 200, 202, 204, 206 and 208 are operable to detect parameters of structure 100 related to its structural integrity. Each of sensors 200, 202, 204, 206 and 208 may detect one or more parameters, but not necessarily the same parameters, related to structural integrity of structure 100. Data processing unit 210 is operable to read the parameters detected by sensors 200, 202, 204, 206 and 208.
Wireless sensors 200, 202, 204, 206 and 208 are operable to wirelessly communicate with data processing unit 210.
In conventional monitoring system 212, the operational energy of wireless sensors 200, 202, 204, 206 and 208 are supplied either through batteries and/or energy harvesting processes.
In operation, conventional structural health monitoring system 212 monitors structural health and integrity of structure 100 by gathering and processing information from sensors 200, 202, 204, 206 and 208. For example, if sensor 200 is capable to monitor strain, it regularly provides readout of strain to data processing unit 210. Then data processing unit 210 may develop baseline range for normal strain readout for sensor 200 by examining long term readouts of sensor 200. After developing the baseline range, if the strain readout of sensor 200 is outside the normal baseline range, data processing unit 210 may generate an alarm. In a similar manner, data processing unit 210 processes data provided by sensors 202, 204, 206 and 208.
Sensors 200, 202, 204, 206 and 208 in conventional structural health monitoring system 212 require batteries in them to supply their electrical energy. As a result, the batteries in sensors 200, 202, 204, 206 and 208 run out of energy after a certain period of time since batteries need periodic maintenance and replacement even if they are connected to alternative power sources. Therefore, conventional structural health monitoring system 212 requires regular battery replacement for sensors 200, 202, 204, 206 and 208.
What is needed is a structural health monitoring system in which a large number of sensors can be easily attached to a structure without need for wiring.